/ic/ - Artwork/Critique

This might sound like the most amauterist thing ever, but I've been looking at some videos and one stuck with me.

https://www.youtube.com/watch?v=DbLECin_UPE

You don't need to see the whole 2 hours, just hop around the beggining.

The work flow this guy uses looks really simple and I've been trying to incorporate that to my own, but I've had some difficulty. See, he first sketches the whole thing, and from there, shapes it up, on the same layer. Thing is, maybe it's his brushes or whatnot, but I can't for the love of me reproduce it. Every brush I have, either my own or downloaded, looks super "smudgy" and blurry, so the draft ends up just as smudgy and blurry.
Anybody had this problem as well and overcame it? I've tried so many things already to no avail.